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  #1  
Old Oct 17th, 07, 03:39 PM
kooter454 kooter454 is offline
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Default rear end swap

I have heard that a 9inch from a 1960 t-bird will bolt up in my 70 nova with minor problems, Does any one know if this is true? of course I know the wheels won't bolt up but are they the same with or close enough to work? thanks for any help
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  #2  
Old Oct 17th, 07, 06:18 PM
Big Dave Big Dave is offline
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Cool Re: rear end swap

This is a condensed version of a Q & A spanning many weeks and pages on another forum that I think answers all the 9" Ford vs GM rear end questions. I didn't write every word but it raises questions that need answering.


10 and 12 bolt GM rears are basically weak everyone "KNOWS" that 9 inch Ford rears are stronger. A 12 inch can not handle more than 450 hp.

I beg to differ on the statement "it's still not as strong as the 9". The "new" Moser 12 bolt will handle up to a thousand horse with the 31 spline axle package. A stock 30 spline 12 bolt still is and always was stronger than a stock 9" (people only stopped using them because there were no more around). Even a custom built 9" without a Ford part in it isn't that much stronger than the "new" Moser 12 bolt. The Moser is a all new non-GM high nickel casting with heavy fully welded axle tube walls and no C-clips. I've used one for years with over a thousand horse in a 4000+ pound car and it hasn't given a moments bother. It also doesn't suffer from the parasitic drag that the 9" does so more of your horse power gets to the ground than goes into frictional losses. I'd choose a Dana 60 over a Ford 9" any day of the week, and the Dana 60 is a real boat anchor at 287 pounds compared to the 185 pounds for the 12 bolt.

The big boys abandoned the 9" years ago because they are too weak to hold up to more than two thousand horse power. Though it looks like a 9" in the rear of those top fuel cars it is actually a purpose built 11" rear end. They took the 9" design and super sized it (as in would you like fries with that).

You don't even have to take the brakes off the car to install another 8.5" 10 bolt or 12 bolt GM rear end. Just unbolt the backing plates and let em hang, remove C clips and the axles, and install the rear end then bolt up the backing plates, and drive !!!! Its really that easy. Your brakes will work with an aftermarket 9 inch if it is ordered correctly. You still must get the correct housing ends to use the Chevy brakes. You will also have to bore a hole in the center of the backing plates to 3.150 inches in diameter to go over the axle wheel bearings.

Another alternative is a new Dana 60 if weight isn't a concern. The base model has 35 spline axles, a 1350 yoke and (of course) no c-clips. The axles on that thing are massive and it's way overkill for most street setups. Moser makes a complete new assembly for a little cheaper than the price for their new 12 bolt GM setups. Strange and others make them too. The Moser 60 is a direct bolt in; if ordered with brakes, and TruTrac. The advantage of ordering a new setup is that you can order it with whatever options (shortened, brakes, housing ends, dual wheel stud pattern, choice of posi and gears, etc.) you want or can afford and it's put together by someone who does it for a living. (If you think I work for Moser, I donít, Currie offers the same Dana 60 set up)

If you decide to hunt for a boneyard special, you will need new shocks to control that added weight, and unless you are buying aftermarket the axles needs to be drilled for 4-3/4" bolt pattern or add the expense of new wheels as well as new brakes. You can find many cheap Dana 60's under MoPar and FoMoCo trucks (and early GM trucks as well, just be sure it's a Dana and not a Spicer 14" because they look a lot a like).

The Dana 60 has a 9 3/4 diameter ring gear, which is almost a full inch larger than the 12 bolt and 3/4 inch larger than the 9 inch Ford. It also has 35 spline axles, 5 more than the 12 bolt and 4 more than the 9 inch. These are some of the things that make one rear end stronger than another. Some of the weaknesses of the 60 are the smaller diameter pinion head (in the much lower gear ratios) and it tends to spin the differential bearing race in the housing, which will damage the housing.

By low do you mean like 4:11's and lower? Is the MOSER 60 the exact same as the Dana 60's? I know the Mosers 12 bolts are supposed to be made better than the stockers . The Moser 12 bolt upgrade is 33 spline.

Big Gear Head is talking about when you get into the high 5's and 6"s for rear gears (They make up to a 7.88 gear for it).

That is correct. When the gear ratio gets into the 6.xxs the pinion gear is pretty small and becomes a weak link.

The Dana 60 is a Mil spec component. It doesn't fail. They are used on all military trucks up to one ton and have been used in service since Viet Nam were they first appeared under military transports. It was chosen by all of the Top Fuel guys to replace the Olds rear when horse power numbers out stripped the performance potential of the Olds-Pont Salisbury style rear ends. Mopar used them in their Hemi and 440 six pack street cars and of course Mopar and Ford still put them under 3/4 and 1 ton trucks (GM uses them in 1 tons also). They are just about unbreakable.

You say it's 100 pounds more than the 12 bolt?? How much does the 8.2 10 bolt weigh compared to the 12bolt? If I WAS considering the nine bolt how much more would the Dana weigh compared to that?

You can never get a straight answer to this question because no one runs a stock 9". Matter of fact there are precious few to any stock parts in any 9" rear end especially if it is made for a non-Ford application. I have three examples of rear ends I have pulled and weighed. Maybe gravity is different were you live (remember the higher up you go the less a item weighs).

Complete drum to drum the 10 bolt weighs on average (that means the one I weighed was an average rear end out of a '74 Nova with multi-leaf spring perches attached) 179 pounds.

An open rear 12 bolt out of a '70 Chevelle weighed 185 pounds, missing the passenger side drum.

9" weighs 230 pounds (Currie Fab 9 housing, Nodular case) Off of Curries web site.

A Dana 60 rear end out of a Road Stumbler with the pinion snubber and two "big" (though stock) drums came in at 287 pounds.

Any way you slice it the 12 bolt is lighter and just as strong as anything you could bolt up. The 9" has a minimum of a 3% higher parasitic drag cost than the Spicer design (We know them as 10 bolts and 12 bolts but it also applies to the Dana rear end; most people say the 9" will cost you at least 4% off of whatever horse power you make just to spin it). And My favorite reason to use a 12 bolt under a Chevy; it is genuine GM product so it looks right (less filling - looks right -- less filling).

Please note that they forgot to weight the 9" axle with the backing plates, wheel cylinders, brake hardware, shoes, and those pesky cast iron brake drums on that weight chart.

This is an example of how the car magazines; which some say are basically just infomercials for the advertisers, slant things in favor of the product they are showcasing. They did not lie (there are laws against that kind of behavior), but a fast reader would be prone to over look the disclaimer in the parenthetical brackets.

As I pointed out when it came to weights and measures for a 9" it all depends upon what you are measuring because no two are alike. The 9" currently being sold is a concept not a product. It can be anything from a fabricated titanium housing, with a magnesium and aluminum cased carrier sporting gun drilled axles and a titanium spool to a slab of wrought iron and cast iron, with forged tool steel propeller shafts off a tug boat being used by some cow poke that he built for his 4x4 to crawl around a bit in Utah. There really needs to be some definitive standard as to what a 9" inch rear is and add or subtract weight as you modify it (with the modifications noted).

I have a hard time believing that the 9" is costing me 4% of my rear wheel power. Would swapping to a 8.5" 4.10 turn my 11.75@117 second daily driver/tow car into a 11.60@119 second monster? We already get 417 rwhp from our relatively mild 331" road race motor, would this mean 434 rwhp? Other than speculation, is there any definitive A-B-A testing of this supposed loss?

As to the 4% parasitic drag. Were do you think the strength of the 9" comes from. Surely you are not going by just the diameter of the ring gear because the 12 bolt is the same size. In fact Strange sells a 9" rear end equipped with the ring and pinion out of a 12 bolt Chevy to overcome the parasitic drag issue. No the strength of the 9" Ford design lies in the fact that it located the pinion gear low on the ring gear so that it engages two teeth of the ring gear at a time instead of the one tooth at a time that the Spicer design uses. Because it is dragging twice the number of teeth across the ring gear it has more friction. That friction is what we call parasitic loss. And yes it has been measured and compared a number of times.

The problem in testing is depending upon how you set up the rear end (back-lash, side load, pinion depth and crush on the bearings) there is a difference even between two similar rear ends made by the same person using the same parts. Because of this the 9" guys throw there hands up and say "See, I told you it's inconclusive." even though hundreds of tests all indicate a 3-4% loss.

Big Dave with a little help from his friends (such as Freddie aka "Big Gear Head")
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  #3  
Old Oct 17th, 07, 06:42 PM
jim454 jim454 is offline
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Default Re: rear end swap

Not sure if the 60 9" is the same width as the 70 10 bolt ,measure it .You could always cut the spring perches off and relocate them if it is .I personally would look for a descent 12 bolt posi unit that will bolt right in for that 70 nova.The parts that you can get for those cars is staggering.
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Old Oct 17th, 07, 07:10 PM
big gear head big gear head is offline
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Default Re: rear end swap

The '60 T bird 9 inch is going to have 28 spline axles in it, the same as your 10 bolt. In stock form the 9 inch isn't much better than the 8.2 10 bolt, and probably not as good as the 8.5 10 bolt. If you want a strong 9 inch you have to put in the right parts. With that said you can do the same thing for the 8.5 10 bolt and have a lighter rear end that will take less power to turn. You also avoid the modifications required to install the 9 inch.
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  #5  
Old Oct 19th, 07, 08:49 PM
Doug G Doug G is offline
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Default Re: rear end swap

I like the 8.5" as for parts and strength. 12bolts are hard to find and then expensive, might as well go aftermarket and get all new, better stuff.

8.5's easier to find (cheaper) and with aftermarket parts will be fine IMO ...and said to handle 600hp ?
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  #6  
Old Dec 27th, 07, 03:46 PM
62convertible 62convertible is offline
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Default Re: rear end swap

I just recentley purchased a shortened 48 inch ford 9 inch rear end. It is set up for coil springs and ladder bars. I was wondering if someone could suggest some coil springs and ladder bars that would would work with my 62 nova i was also wondering if i am going to have to tub it on account of the shortened rear end. Thank you
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Old Dec 27th, 07, 08:52 PM
Gloryhound Gloryhound is offline
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Default Re: rear end swap

Quote:
Originally Posted by 62convertible View Post
I just recentley purchased a shortened 48 inch ford 9 inch rear end. It is set up for coil springs and ladder bars. I was wondering if someone could suggest some coil springs and ladder bars that would would work with my 62 nova i was also wondering if i am going to have to tub it on account of the shortened rear end. Thank you

Your looking at some serious modifications and I'm not sure if a convertible is going to deal well with a tub job. If I remember right they have trouble with even installing mini tubs. You may be able to avoid it with that rear end if you use spacers and such, but I have to ask are you planning on building a full frame for the car? Due to the the Nova being a semi uni-body and yours as a convertible I don't think the body has enough strength to stand up to the abuse of ladder bars even with subframe connectors. If your looking for a strip car the last type of car you really want is a convertible. Might save some weight, but you loose a lot of strength.
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  #8  
Old Dec 28th, 07, 06:35 PM
62convertible 62convertible is offline
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Default Re: rear end swap

I'm not trying to build a strip car i just wanted a reliable posi rear end and a came across a deal for the rear end and muncie four speed. The rear end was on a 66 nova for 5,000 miles and the mounts are already welded. Since the rear end is shortened the beginning of the axles start at the end of leaf springs so i don't have option of using them. I am only putting in a 400 horsepower small block 327. Will that be to much power, what else could i do to with the rear end suspenion? Maybe buy a 4 link supension any suggestions will help thank you.
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Old Dec 28th, 07, 08:34 PM
Big Dave Big Dave is offline
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Default Re: rear end swap

If it will fit a 1966 it will fit your car.

Provided they did not narrow the rear end to allow for big tires to fit into a tubbed back half of the car. If the old 1966 was stock it will fit your stock 62 just as well.

But no one goes to the trouble and expense of removing a perfectly good stock rear end and replacing it with a non-stock rear end from a different make, and leaving everything else stock. That is just throwing away a lot of money for no reason. So we can assume (safely I think) that you have a narrowed drag car rear end set up for a quarter mile blast designed to clear nice big sticky slicks that will not fit under your car with out a lot of fabrication and money.

If that is a "good deal" I do not know, but if you are not going to race your car then the stock rear end will work just fine with stock sized street tires; regardless of the number of horses you make because the tires will just slip. You only need big strong rear ends if you plan on trying to force a lot of power to the ground planted with slicks. An open stock rear end makes a fine one tire on fire burn out car to impress your friends.

Big Dave
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Old Dec 28th, 07, 10:22 PM
Gloryhound Gloryhound is offline
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Default Re: rear end swap

Also you could just get a posi kit to go into your existing housing if you really want posi! You may even get lucky and find someone trying to build an all out drag car that would pay cash for what you have or since it is already made for a 66 Nova and 1st or 2nd gen Nova guy building a drag car might be willing to swap for their rearend which may be an aftermarket posi or something as they have been building the car up slowly over time.
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  #11  
Old Jan 7th, 08, 12:10 PM
62convertible 62convertible is offline
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Default Re: rear end swap

I will be replacing the rear pan anyways due to some rust so as that point i was planning on tubbing it. The rear end has mounts on it for coil springs and ladder bars, i was just going to purchase a 4 link rear suspension. I don't need anyone to tell me how much going to have spend and how much work its going to be, i know, every corner i turn i seem to get that answer. I would like some suggestions on what companies to look in to for 4 link supension. On the 66 nova my rear end was previously on they had 12 inch wide tires without tubbing it. I was thinking maybe with 10 inch tires and possibly spacers i wouldn't have to tub it? Thank you
Graham Wolfe
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  #12  
Old Jan 7th, 08, 03:27 PM
Big Dave Big Dave is offline
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Default Re: rear end swap

Graham my favorite mail order chassis guy is Art Morrison. He sells a mail order back half chassis kit with a four link if that is what you want, he also sells four bar set up, three link floaters, or ladder bars if you want. He also sells mail order tubs that will swallow a 14" x 32" slick. The rear frame comes with a 9" housing already welded up and ready for your 9" pumpkin to be installed; just have to bolt it up with suspension pieces. He catalogue is on line and he works out o your neck of the woods.

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